Distillation Design Questions and Answers Part-4

1. Separation of a volatile mixture of relatively pure products, is done in a
a) Steam distillation
b) Fractionating Column
c) Flash Distillation
d) Depending of product required

Answer: d
Explanation: The separation always depends on the quality of product required independent of operation required

2. McCabe Thiele is based on the assumption?
a) Constant molar overflow
b) Constant reflux ratio
c) Volatile products are used for better separation
d) Boil up ratio is infinity

Answer: a
Explanation: The best assumption of the McCabe Method is it is based on Constant molar overflow, while heat duties are neglected in the method.

3. The vapor rich section in the distillation column is called as
a) Rectifying Section
b) Boiling section
c) Stripping Section
d) Leaching section

Answer: a
Explanation: The part above the feed tray is rich in vapor which is called as rectifying or enriching section and contains only vapor in equilibrium with liquid.

4. The liquid rich section in a distillation column is called as
a) Boil up section
b) Reflux section
c) Stripping Section
d) Enriching Section

Answer: c
Explanation: The part below the feed tray is enriched with liquid feed which is called as Stripping Section and contains only liquid at the column temperature.

5. The feed of a distillation column is related to be a
a) Binary mixture
b) Urinary mixture
c) Mixture of phases
d) Tertiary Mixture

Answer: d
Explanation: Mixture of phases i.e. two phase mixture is necessary for distillation, either it can be a multicomponent mixture as per required conditions.

6. The equilibrium curve of the column is given as
a) yn=x
b) y*=x
c) yn+1=xn
d) xn+1=y

Answer: c
Explanation: The equilibrium curve is the locus of all equilibrium point given as yn+1=xn, while y*=x represents the equilibrium relation of gas and liquid.

7. The feed line equation is given by
a) F – L = q
b) L’ – L = qF
c) V – V’ =F
d) F = L – V

Answer: b
Explanation: The feed line equation is L’ – L = QF where q is the product of quantity of liquid contained in feed.

8. The overall Energy balance of a column is given by
a) V1HV1 = L0HL0 + DHD + QC
b) QC = V1HV1
c) V1HV1 = DHD + H0
d) Can change with models

Answer: a
Explanation: The energy balance equation is given as V1HV1 = L0HL0 + DHD + QC, where Qc is the heat provided through reboiler.

9. If the liquid flow rate is 212 and vapor flow rate is 284, then the slope of rectifying section is?
a) 0.55
b) 0.89
c) 1.33
d) 0.75

Answer: d
Explanation: As slope is given by L/V = 212/284 = 0.75

10. If 0.75 is the fraction of liquid in the feed, Estimate the feed line slope?
a) -2.0
b) -1.5
c) -3.0
d) Cannot be calculated

Answer: c
Explanation: As given q=0.75 then feed slope is given by q/q-1 = 0.75/-0.25= -3.0.